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When merging adjacent operands, scan ahead and merge all equal

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adjacent operands at once, instead of just two at a time.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@112299 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman 2010-08-27 21:39:59 +00:00
parent b5b21e5672
commit 68ff776661
1 changed files with 14 additions and 11 deletions
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25
lib/Analysis/ScalarEvolution.cpp
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@ -1412,22 +1412,25 @@ const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
if (Ops.size() == 1) return Ops[0];
}
// Okay, check to see if the same value occurs in the operand list twice. If
// so, merge them together into an multiply expression. Since we sorted the
// list, these values are required to be adjacent.
// Okay, check to see if the same value occurs in the operand list more than
// once. If so, merge them together into an multiply expression. Since we
// sorted the list, these values are required to be adjacent.
const Type *Ty = Ops[0]->getType();
bool FoundMatch = false;
for (unsigned i = 0, e = Ops.size()-1; i != e; ++i)
for (unsigned i = 0, e = Ops.size(); i != e-1; ++i)
if (Ops[i] == Ops[i+1]) { // X + Y + Y --> X + Y*2
// Found a match, merge the two values into a multiply, and add any
// remaining values to the result.
const SCEV *Two = getConstant(Ty, 2);
const SCEV *Mul = getMulExpr(Two, Ops[i]);
if (Ops.size() == 2)
// Scan ahead to count how many equal operands there are.
unsigned Count = 2;
while (i+Count != e && Ops[i+Count] == Ops[i])
++Count;
// Merge the values into a multiply.
const SCEV *Scale = getConstant(Ty, Count);
const SCEV *Mul = getMulExpr(Scale, Ops[i]);
if (Ops.size() == Count)
return Mul;
Ops[i] = Mul;
Ops.erase(Ops.begin()+i+1);
--i; --e;
Ops.erase(Ops.begin()+i+1, Ops.begin()+i+Count);
i -= Count - 1; e -= Count - 1;
FoundMatch = true;
}
if (FoundMatch)